A luminaire or light fixture includes at least a light source (or lamp), electrical components and a housing. A standard luminaire for illumination of surfaces, areas or objects typically uses a single light source and may include an optical arrangement to control raw light output from the single light source for more efficient distribution of the light. The optical arrangement can be a lens, a refractor, a reflector, or a combination of these optical elements that controls the light and produces a desired illumination pattern or distribution.
Most standard lamps come in very high wattages and can produce high lumen outputs. Light emitting diodes (LEDs) differ in that they are low wattage but they have increased in efficiency so as to make them practical for use in lighting systems. Previously, these devices were not sufficiently efficacious compared to a standard light source such as fluorescent, high intensity discharge, or incandescent. As with all light sources, the total light output of LEDs requires optical control to make it perform properly and maximize the light coverage over a surface or area.
In order to produce the equivalent amount of light of a high wattage standard lamp source, a large array of LED can be used although LEDs also differ in their raw light output. Most standard lamp sources produce a radial illumination pattern that is generally uniform in all directions and emanates from a single area on or within the lamp such as a filament or arc tube. However, LEDs produce a Lambertian distribution which only emanates from the front of the diodes and is not uniform in all directions. As such, most LEDs have a built-in lens to control the raw light output in a primary fashion, but a primary lens or optic has not proven to provide the necessary optical control to provide illumination patterns that are suitable to replace standard luminaire optical systems and lamp sources.
Problems with direct replacement of standard lamp sources stem from the inability to mimic the emanation of the standard sources raw light output. As notably stated, an array of multiple LEDs must be used to replace a standard light source, where each diode is a point source such that the array of diodes comprises multiple point sources spread over an area within the lighting fixture or luminaire. Individual diodes of the array must also be spaced apart for heat dissipation, a critical aspect of LED system design. Thus, standard optical systems are often useless for LED systems as they are designed around a point source, linear source, or small area source.
Some LED systems may use a secondary-type optic repeated over each individual diode of the LED array. These types of LED systems have not yet proven to exceed the light distributions of standard lamp sources. Typically, their distributions fall short or they have similar amounts of waste light due to only having one level of control used over the LED array.
Thus, it is desirable to provide an LED array with primary optics and multiple levels of secondary optics, where each level of secondary optics can be precisely aimed so that the array provides a more uniform distribution. It is desirable for such an LED array to have a larger, more efficient light distribution and meet or exceed standard type lamp systems. In a practical manner, an LED system with multiple levels of secondary optics would be superior as these secondary optics can be aimed and combined to produce different distribution shapes to more effectively light surfaces or areas.